Coolant is critical for the engine, but checking it needs to be done properly. The most important rule is simple: do not open the expansion tank or cap when the engine is hot, because the system may still be under pressure.
The safest time to check the level is when the car has been standing and the engine is fully cold. Most expansion tanks have minimum and maximum marks that quickly show whether the level is still in the normal range.
If you constantly need to top up coolant, that is not normal. It often points to a leak, a loose connection or a larger fault that should not be hidden by repeatedly adding more fluid.
It is also not wise to mix random coolant types. If you do not know what is already in the system, check the manufacturer guidance or have it inspected. The right information saves both money and trouble later.